The Heidelberg Catechism

A. Because God's righteousness requires that man
who has sinned should make reparation for sin, but the man who is himself a sinner cannot
pay for others.

Q. 17. Why must he at the same time be
true God?

A. So that by the power of his divinity he might
bear as a man the burden of God's wrath, and recover for us and restore to us
righteousness and life.

Q. 18. Who is this mediator who is at
the same time true God and a true and perfectly righteous man?

A. Our Lord Jesus Christ, who is freely given to us
for complete redemption and righteousness.

Q. 19. Whence do you know this?

A. From the holy gospel, which God himself revealed
in the beginning in the Garden of Eden, afterward proclaimed through the holy patriarchs
and prophets and foreshadowed through the sacrifices and other rites of the Old Covenant,
and finally fulfilled through his own well-beloved Son.